1. Field of the Invention
The invention relates to an antenna for a read/write unit for Radio Frequency Identification (RFID) arrangements, a read/write unit for RFID arrangements, a system comprising a read/write unit for RFID arrangements and an external antenna, and a method for matching the read/write unit for RFID arrangements to an external antenna.
2. Description of the Related Art
Read/write units for Radio Frequency Identification (RFID) arrangements, such as in the Ultra High Frequency (UHF) band, are frequently operated with external antennas, particularly in the case of arrangements in which an internal antenna alone is not sufficient for covering a required radio area. For example, it is possible to equip a loading door in logistics with four antennas for the purpose of better radio coverage, all four antennas being connected to a single read/write unit (“Reader”), where alternate operation of the various antennas is implemented in the read/write unit via a changeover matrix, for example.
At least when the RFID arrangement, i.e., the read/write unit and the antennas, is installed for the first time, a user needs to carefully parameterize the antenna lines and antennas used in the read/write unit when configuring the read/write unit. For example, it is necessary to reduce the maximum transmission power as the antenna gain rises, in order to comply with legal requirements. On the other hand, in the case of antenna lines or in the case of connections between the radio-frequency circuit of the read/write unit and the radiation element of the antenna, losses may arise, depending on the damping and depending on the adjustment (e.g., reflection factor), which can or are permitted to be compensated for by a higher transmission power for the read/write unit. Only exact configuration of the read/write unit in respect of the type or properties of the antenna used and the properties of the antenna line (cable) used results in the desired or permitted radiation power and, on the other hand, a misconfiguration, such as cable damping which is set too high, may possibly result in the permissible radiation power being exceeded.
To configure a read/write unit with respect to “antenna configuration”, it is necessary to manually input, for each “antenna port” used, i.e., for each antenna connection, what line parameters (e.g., cable damping) and what antenna (type or antenna gain) are used. Firstly, this is complicated for a user, because he may need to look up what values need to be set in manuals, tables or the like, and secondly legal requirements may be infringed or else malfunctions may occur as a result of incorrect inputs. In addition, there is the danger of the configuration not being adjusted when the operating frequency is changed, when an antenna is replaced or when an antenna line is replaced, as a result of which faults or impermissible operating states can likewise occur.